Midterm Exam

Question 1

Chemical Properties

Answer 1

flammability, toxicity, reactivity, combustion, acidity

Question 2

Physical Properties

Answer 2

density, color, hardness, reflectivity

Question 3

chemistry

Answer 3

the branch of science that deals with the properties, composition, and structure of elements and compounds

Question 4

Scientific Method

Answer 4

1. observe
2. state the problem
3. form a hypothesis
4. test hypothesis
5. draw a conclusion
6. communicate results

Question 5

hypothesis

Answer 5

testable prediction

Question 6

theories

Answer 6

generalizations made from many experiments

Question 7

laws

Answer 7

generalizations that allow us to predict how things in nature will behave

Question 8

SI Units

Answer 8

length: meter
mass: kilogram
time: second
temperature: kelvin
amount of a substance: mole
electric current: ampere
luminous intensity: candela

Question 9

Dalton’s atomic theory

Answer 9

1. all matter is composed of extremely small particles called atoms (wrong)
2. atoms of a given element are identical in size, mass, and other properties (wrong)
3. atoms cannot be subdivided, created, or destroyed (wrong)
4. atoms of different elements combine in simple whole number ratios
5. in chemical reactions, atoms are combined, separated, or rearranged

Question 10

law of conservation of mass

Answer 10

matter cannot be created nor destroyed by normal means

Question 11

law of conservation of energy

Answer 11

energy cannot be created nor destroyed but may be converted from one form to another

Question 12

law of definite proportions

Answer 12

compounds are made up of the same ratio of elements no matter how much there is or where they are found

Question 13

law of multiple proportions

Answer 13

if two or more compounds are composed of the same elements, then the ratio of the masses of the second elements combined with a certain mass of the first will always be small, whole numbers

Question 14

Thomsons’ Cathode Ray Tube Conclusions

Answer 14

1. electricity is composed of particles of matter (electrons)
2. electrons are negatively charged
3. electrons are very small

Question 15

Oil Drop Conclusions

Answer 15

1. mass of an electron is 1/2000 of a hydrogen atom
2. same charge, but negative

Question 16

Rutherford’s Gold Foil Conclusions

Answer 16

1. the atom is composed of mostly empty space
2. there is a small but very dense central core (nucleus)
3. the nucleus has a positive charge

Question 17

properties of neutrons

Answer 17

1. about 1 amu
2. neutral charge
3. located in nucleus

Question 18

properties of protons

Answer 18

1. about 1 amu
2. positive charge
3. located in nucleus

Question 19

properties of electrons

Answer 19

1. about 1/2000 amu
2. negative charge
3. located in electron cloud

Question 20

atomic number

Answer 20

number of protons in an elements atom

Question 21

mass number

Answer 21

the sum of the protons and neutrons
(always whole numbers)

Question 22

Bohr Model

Answer 22

1. electrons exist only in orbits with specific amounts of energy called energy levels
2. electrons can only gain or lose certain amounts of energy
3. only certain photons are produced
4. energy of photons depends on the difference in energy levels
5. each element has a unique bright-line emission spectrum

Question 23

Quantum Theory

Answer 23

Planck:
observed: emission of light from hot objects
concluded: energy is emitted in small, specific amounts (quanta)
quantum: minimum amount of energy change
Einstein:
observed: photoelectric effect
concluded: light has properties of both waves and particles

Question 24

Heisenberg Uncertainty Principle

Answer 24

impossible to know both the velocity and position of an electron at the same time

Question 25

Schrodinger Wave Equation

Answer 25

1. finite number of solutions -- quantized energy levels 2. defines probability of finding an electron

Question 26

Principle quantum number

Answer 26

(n) -- energy level size of the orbital n^2 -- number of orbitals in the energy level

Question 27

Angular momentum quantum number

Answer 27

(l) -- energy sublevel shape of the orbital (s, p, d, f)

Question 28

Magnetic quantum number

Answer 28

(ml) -- orientation of orbital specifies the exact orbital within each sublevel orbitals combine to form a spherical shape

Question 29

Spin quantum number

Answer 29

(ms) -- electron spin (+1/2 or -1/2) an orbital can hold two electrons that spin in opposite directions

Question 30

Aufbau Principle

Answer 30

electrons fill the lowest energy orbitals first

Question 31

Pauli Exclusion Principle

Answer 31

no two electrons in an atom can have the same 4 quantum numbers

Question 32

Hund's rule

Answer 32

within a sublevel, place one electron per orbital before paring them

Question 33

Periodic law

Answer 33

when elements are arranged in order of increasing atomic number, elements with similar properties appear at regular intervals

Question 34

Ionic Bonds

Answer 34

form when electrons are transferred from a metal to a nonmetal

Question 35

Covalent Bonds

Answer 35

form as a result of two atoms sharing electrons

Question 36

Drawing Lewis Structures

Answer 36

1. find total number of valence electrons 2. arrange atoms -- singular atom is usually in the middle 3. form bonds between atoms 4. distribute remaining electrons to give each atom an octet 5. if there aren't enough to go around make double / triple bonds

Question 37

Lattice Energy

Answer 37

amount of energy released when one mole of the substance forms from gaseous atoms

Question 38

VSEPR theory

Answer 38

valence shell electron pair repulsion theory electron pairs orient themselves in order to minimize repulsive forces

Question 39

Chemical formulas

Answer 39

1. what elements make up the compound (symbols) 2. relative amounts (ratios) of each atom (subscripts)

Question 40

London Dispersion forces

Answer 40

attraction between two instantaneous dipoles

Question 41

dipole - dipole forces

Answer 41

attraction between two permanent dipoles polar molecules

Question 42

hydrogen bonding

Answer 42

attraction between molecules with N-H, O-H, F-H bonds extremely polar bonds